Semiconductor vacuum deposition system and method having a reel-to-reel substrate cassette

ABSTRACT

A substrate cassette contains two physically spaced and parallel reels. A relatively long web of flexible substrate material is wound about one reel and the exposed end of the web is connected to the other reel, to thus expose a relatively short length of the substrate material at a deposition-plane that lies between the two reels. A first idler roller is associated with the first reel, a second idler roller is associated with the second reel, and the web is guided by the two idler rollers as the web moves between the two reels. The two idler rollers are mounted at fixed positions in order to accurately establish a fixed-position deposition-plane. The substrate cassette is placed within one or more vacuum deposition chambers, the web is advanced between the two reels, and one or more semiconductor layers are deposited on substantially the entire length of the web. A protective layer is provided as part of the web in order to protect the semiconductor layer(s) when the web is wound unto a take-up reel. A constant tension is maintained in the web as the web advances from one reel to the other. The two opposite ends of the web are clamped to the two reels by the operation of an axially-split cylindrical cover that covers each reel and is compressed down onto each web end.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority date of copendingprovisional patent application Ser. No. 60/142,374 filed on Jul. 6, 1999for CLUSTER TOOL VACUUM DEPOSITION SYSTEM HAVING A REEL-TO-REELSUBSTRATE CASSETTE

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to the field of material deposition, andmore specifically, to the deposition of one or more semiconductorlayers/films onto a substrate member.

[0004] 2. Description of the Related Art

[0005] It is known in the field of semiconductor manufacturing thatsemiconductor material be selectively deposited onto a substrate member.In so doing, it is known that an in-line horizontal, and in-linevertical, or a circular assembly of vacuum deposition chambers may beused wherein the substrate member is sequentially moved from one chamberto another as is needed to achieve a desired sequence of semiconductorlayers on the substrate member.

[0006] It is usual that the limited internal volume of a vacuumdeposition chamber limits the physical size of a substrate member thatcan be inserted into the chamber(s), and upon which semiconductormaterial may be deposited.

[0007] It would be desirable to provide a means whereby a substrateholder would enable a larger area of substrate to be operated upon by adeposition chamber(s).

SUMMARY OF THE INVENTION

[0008] This invention provides a substrate cassette for use in a singlechamber deposition system for use in an in-line multiple chamberdeposition system, and for use in a circular multiple chamber or clustertool deposition system.

[0009] A substrate cassette in accordance with this invention containstwo physically spaced and parallel reels, either of which can bedesignated as the supply reel, whereupon the other reel becomes thetake-up reel. A relatively long and linear web of flexible substratematerial (for example, a stainless steel or plastic substrate materialthat is about 0.003-inches thick), about 1-foot wide and about 100-feetlong, is wound about the supply reel, and the 1-foot wide exposed end ofthe web is connected to the take-up reel. In this way, a relativelyshort length (for example, 1-foot by 1-foot square) of the substratematerial is supported in a deposition plane, usually either vertical ora horizontal plane, that lies between the supply reel and the take-upreel.

[0010] In an embodiment of the invention, a protective backing web isprovided adjacent to the back side of the substrate web, this protectiveweb operating to protect a deposition layer(s) that is carried by thedeposition side of the substrate web.

[0011] In an embodiment of the invention wherein a single layer of asemiconductor material is to be deposited on substantially the entire100-foot length of the substrate web, the substrate cassette of theinvention is placed in a deposition chamber, and a relatively short1-foot length of the substrate is exposed to the deposition volume ofthe deposition chamber. A reel-to-reel servo system then operates toadvance the substrate from the supply reel to the take-up reel at arelatively slow but constant speed, while maintaining a constant tensionin the web, as substantially the entire 100-foot length of the substrateweb receives a deposited layer; for example, a semiconductor layer, ontoone side surface of the web. The end result is a take-up reel havingabout 100 feet of substrate material that contains a single depositionlayer.

[0012] Embodiments of the invention provide for the deposition ofmultiple layers onto the long substrate web.

[0013] In a first embodiment wherein multiple layers are produced, afirst layer is deposited on the entire 100 foot length of the substrateweb as above described. The substrate web is then rewound from thetake-up reel back onto the supply reel, and the above-described processis repeated in order to deposit a second and usually different layeronto the first layer. Of course, this process can be repeated N times inorder to deposit N layers onto the 100 foot length of the substrate web.While it may be preferred to rewind the substrate web between use of thecassette in another deposition chamber, it is within the spirit of theinvention to eliminate this rewind step, and to rewind the substrate webfrom the take-up reel to the supply reel as deposition of a second layeris taking place in the second deposition chamber.

[0014] In a second embodiment wherein multiple layer structures areproduced, the substrate cassette of the invention is placed in a firstdeposition chamber, and a relatively short length of the substrate isexposed to the deposition volume of the first deposition chamber. Afirst layer is then deposited on this first length of the substrate web.The cassette is then moved to a second deposition chamber, and a secondlayer is deposited on the substrate's first length of the substrate web.In this manner, the cassette is moved between a number of depositionchambers as a like number of layers are deposited on the first length ofthe substrate web. Once all layers have been deposited on the firstlength of the substrate web, a reel-to-reel servo system operates tostep advance the substrate web to expose a second length of thesubstrate at the deposition operative position between the two reels.The cassette is then recycled through the deposition chambers to producea second multiple layer structure on the substrate second length. Inthis embodiment of the invention, when the substrate has been completelywound from the supply reel to the take-up reel, the take-up reelcontains a number of individual substrate areas, each individualsubstrate area containing one multiple layer structure. For example,when the substrate web is about 100-feet long and about 1 foot wide, andwhen each individual substrate deposition length is about 1 foot long,the finished web contains as many as 100 individual multiple layerstructures, each measuring about 1 foot by 1 foot.

[0015] In a preferred embodiment of the invention, a number of vacuumdeposition chambers are mounted in a generally circular configuration soas to occupy a generally common horizontal plane, and acentrally-located vacuum chamber contains a robotic arm that is mountedat a central location relative to the deposition chambers. This roboticarm periodically rotates in the common plane to thereby step transportthe substrate cassette from one deposition chamber to another depositionchamber, as multiple layers are vacuum deposited on the substratemember. In another embodiment of the invention, the multiple vacuumdeposition chambers are arranged in a generally linear or in-linefashion, either horizontal or vertical, and a transport means operatesto step transport the substrate cassette through the depositionchambers.

[0016] A non-limiting use of a single vacuum chamber deposition systemis in the manufacture of a thin semiconductor, such as an amorphoussilicon layer, a thin film amorphous silicon alloy layer, amicro-crystalline silicon, or a polycrystalline silicon layer on arelatively long/narrow and inert substrate web.

[0017] A non-limiting example of the use of such a linear or circularvacuum deposition chamber configuration is in the manufacture of n-i-psemiconductor structures, such as amorphous silicon, micro-crystallinesilicon or polycrystalline type semiconductor on a relativelylong/narrow and inert substrate web. In this use, a first vacuum chamberis used to deposit a n-type layer on the substrate member, a secondvacuum chamber is used thereafter to deposit an intrinsic layer on then-type layer, and a third vacuum chamber is used thereafter to deposit ap-type layer on the intrinsic layer, or three such vacuum chambers canbe used in the opposite sequence to produce p-i-n semiconductorstructures.

[0018] As will be appreciated, deposition chambers other than thoseabove described can be used, as desired, in order to manufacturevirtually any type of semiconductor structure. For example, a depositionchamber can be used to deposit a first metal contact layer on thesubstrate web prior to deposition of the above described firstsemiconductor layer, and yet another vacuum deposition chamber can beused to deposit a second metal contact layer on the last semiconductorlayer; for example, by using techniques such as, but not limited to,metal vapor deposition and metal evaporation.

[0019] The present invention provides a new and unusual substratecassette or substrate magazine physical format that contains arelatively long, narrow and flexible substrate web that is lengthadvanced through a single station deposition system, or through thevarious stations of a multiple station deposition system.

[0020] While the substrate cassette of this invention finds utility inboth single station vacuum deposition systems and multiple stationvacuum deposition systems, the spirit and scope of this invention is notto be limited thereto, since substrate cassettes of this invention areuseful in virtually any deposition system wherein a layer is depositedon the substrate web as the substrate web moves from a first reel,through a deposition area, and then onto a second reel.

[0021] As a feature of the present invention, the substrate cassette ofthe invention includes a first idler roller that is associated with thefirst reel, and a second idler roller that is associated with the secondreel. While the effective diameters of the two reels change as thesubstrate web moves from one reel to the other, the substrate web isguided by the two idler rollers as it moves between the two reels, andthe two idler rollers are structurally mounted to accurately establish adeposition plane whereat deposition takes place along substantially theentire length of the substrate web.

[0022] As another feature of the present invention, each of the tworeels within the substrate cassette is driven by its own electricalmotor, and these two motors are servo-controlled so as to maintain aconstant tension within the relatively short length of the substrate webthat extends between the two idler rollers, thus ensuring that thisshort length of the substrate web is always maintained in one,non-varying, deposition plane.

[0023] As a feature of the invention the two ends of the substrate webare clamped to the respective two reels by the operation of an axiallysplit cylindrical cover that is radially compressed to capture an end ofthe substrate web against the underlying cylindrical surface of a reel.

[0024] These and other features and advantages of the invention will beapparent to those of skill in the art upon reference to the followingdetailed description, which description makes reference to the drawing.

BRIEF DESCRIPTION OF THE DRAWING

[0025]FIG. 1 is a top view of a circular, multiple chamber, vacuumdeposition system having three vacuum deposition chambers, three viewport stations, a combination load lock and park station, and a secondpark station in accordance with the invention, and in which thesubstrate cassette of the invention finds utility.

[0026]FIG. 2 is a side view of a linear, multiple chamber, vacuumdeposition system having three vacuum deposition chambers, an entrycombination load lock and park station, and an exit combination loadlock and park station in accordance with the invention and in which thesubstrate cassette of the invention finds utility.

[0027]FIG. 3 shows one of the three vacuum deposition chambers that areshown in FIG. 1 wherein this chamber includes a substrate cassette inaccordance with the invention.

[0028]FIG. 4 is an enlarged side view of the cassette that is seen inFIG. 3.

[0029]FIG. 5 is a bottom view of the FIG. 4 cassette.

[0030]FIG. 6 is a perspective view of a cassette in accordance with theinvention wherein the cassette deposition plane is accuratelyestablished by a first and a second idler roller.

[0031]FIG. 7 is an exploded view that shows how the supply and take-upreels of FIG. 6 are each constructed and arranged to capture andsecurely hold an end of the cassette substrate web.

[0032]FIG. 8 shows an embodiment of the invention wherein the side ofthe substrate web that faces away from FIG. 6 deposition window includesa protective layer that operates to protect the deposition side of theweb when the web is wound about a reel.

[0033]FIG. 9 shows a vertically-oriented vacuum deposition chamberwherein the chamber includes two vertically-oriented substrate cassettesin accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034]FIG. 1 is a top view of a circular, multiple chamber, vacuumdeposition system 10 having three vacuum deposition chambers 11, 12 and13, three view port stations 14, 15 and 16, a load lock station 17, anda second park station 18.

[0035] The eight above-mentioned stations 11-18 are mounted or locatedgenerally in the horizontal or X-Y plane of FIG. 1, and stations 11-18are located generally on a common circle 19 having a central axis 20that extends in the vertical or Z-direction of FIG. 1. Circle 19 isgenerally defined by the circular cylinder wall 21 of acentrally-located and generally disk-shaped vacuum chamber 22 that isabout 24-inches high (the Z direction), and that contains abi-directionally rotatable robotic arm 23 of conventional and well-knownconstruction that is rotatable about axis 20 and in the horizontal X-Yplane of FIG. 1, this rotation being represented by arrow 26. Roboticarm 23 includes an article grasping end (not shown) that is configuredin a well-known manner to cooperated with the substrate cassette of thisinvention.

[0036] While not shown, a video system is provided withincentrally-located vacuum chamber 22 to enable the process to bemonitored from that viewpoint.

[0037] With reference to viewing stations 14, 15 and 16, these threestations include a generally vertically-extending transparent window bywhich an operator may view internal operations that are taking placewithin centrally-located vacuum chamber 22, and each of these threestations are adapted to expand, or retrofit, the station content of theFIG. 1 system by placing an additional vacuum deposition chamber at oneor more of the viewing stations 14, 15, 16. In the alternative, some orall of the stations 14, 15 and 16 may comprise other types of cassetteprocessing chambers.

[0038] With reference to stations 11, 12, 13, and 17, each of these fourstations comprise a vacuum chamber that includes a gate valve 24. Gatevalves 24 are sealed to centrally-located vacuum chamber 22, and enablerobotic arm 23 to transport a cassette from central vacuum chamber 22 toa selected one of the deposition vacuum chambers 11, 12, 13, 17, withoutsubjecting the cassette and the various vacuum chambers to contaminationor cross contamination As will be appreciated by those skilled in theart, rotation of robotic arm 23 and operation of gate valves 24, iscomputer controller and synchronized by way of an associated processcomputer 100.

[0039] In addition, it is quite likely that the individual radiallylocated vacuum chambers 11, 12, 13 operate at different vacuum (i.e.,below atmospheric) pressures, and at vacuum pressures that are differentthan the vacuum pressure that is within centrally-located vacuum chamber22. The process control of the FIG. 1 arrangement may also be computercontrolled at 100 to equalize the vacuum pressure across any given gatevalve 24, before that gate valve is opened for access by robotic arm 23.

[0040] The deposition method or methods that operate within each of thethree vacuum deposition chambers 11, 12 and 13 are not critical to thisinvention, and may include sputter deposition, reactive sputterdeposition, evaporative deposition, reactive evaporative deposition,Glow Discharge (GD), Chemical Vapor Deposition (CVD), Hot Wire ChemicalVapor Deposition (HWCVD), Plasma Enhanced Chemical Vapor Deposition(PECVD), annealing, planarization, MOCVD, and the like.

[0041] Utility of the invention relative to PECVD includes, but is notlimited to, amorphous silicone (p, i and n) wherein the intrinsic layermay be SiH, a-SiFH, a-SiGe:H, etc.; microcrystalline silicon, intrinsicand doped (n and p type) Si, C, SiC, SiGe, SiN, SiONx; hard coatingssuch as a-C, a-BN, etc.; optical coatings; and electrochromic devices.Such a PECVD technique can employ, but is not limited to, a fixedfrequency of 13.56 MHz, a high excitation frequency in the range ofabout 13.56 MHz to about 150 MHz, it can employ DC or any frequency fromDC to the GHz range, the plasma can be modulated or a pulsed plasmatechnique can be used, or the plasma in the PECVD can be remote.

[0042] The utility of the invention relative to sputtering includes, butis not limited to, metallization such as Ni, Mo, Ag, Al, NiCr, etc.;transparent conducting oxides such as ITO, ZnO, etc.; coatings such asC, BN, antireflective coating such as MgF, SiNx, SiONx and SiOx;transparent conducting oxides, and sputtering can employ either DC or avariable frequency in the DC to the GHz range. These materials arefabricated using a suitable target and using Ar, O2 and other types ofreactant gases, such as H2.

[0043] Relative to hot wire or catalytic CVD utility, the following, butwithout limitation thereto, can be produced, amorphous silicone (p, iand n) wherein the intrinsic layer can be a-SiH, a-SiFH, a-SiGe:H, etc.;microcrystalline silicon, intrinsic and doped (n and p type) Si, C, SiC,SiGe, SiN and SiONx; and dielectric layers including silicon nitride,silicon oxide, silicon oxy-nitride, etc.

[0044] Relative to the evaporation process utility, the sources can bespot, either single or multiple or line sources. Materials to bedeposited include any metals, CIS, individually or as compounds, andincluding gallium, CdTe, individually or as compounds, and oxides suchas silicon oxide, ITO, ZnO, SiNx, SiONx, etc.

[0045] Relative to the MOCVD utility, such utility includes materialssuch as GaAs, GaN, ZnP, CdS, InP, etc., either deposited singly or ascompounds using different gases and liquid type sources.

[0046] Relative to the annealing utility of the invention, materialsproduced can be post-deposition that is treated with a heat source, suchas lamps, IR, etc., in order to obtain desired properties In addition,suitable combinations of process chambers and process technology, withsuitable patterning, apply to solar cells, including but not limited toamorphous silicon, microcrystalline silicon, thin film silicon, andrelated alloys that may include Ge, C, N and/or F; thin film transistorswith doped layers, with SiNx as the gate dielectric, and which mayinclude SiNx as the passivation layer, or in an inverse configuration;imaging devices using a p-i-n or a p-n configuration; solar cells usinga CdTe or a CIS configuration; electrochromic devices; hard coatings;and optical coatings in single or multi-layer configurations.

[0047] Relative to load lock station 17 of FIG. 1, this station includesan input load lock 25 that facilitates the manual or automatic input orremoval of a cassette into or out of deposition system 10. In eithercase, the pressure within load lock station 17 is controlled to be atambient atmospheric pressure for either a cassette load or a cassetteunload operation, and before input load lock 25 is opened.

[0048] After a cassette has been loaded into load lock station 17, inputload lock 25 is closed. The vacuum in chambers 17 and 22 is thenequalized, and the gate valve 24 that lies between these two chambers isopened. Robotic arm 23 now enters chamber 25, the article grasping endof robotic arm 23 physically grasps or lifts the cassette, and roboticarm 23 withdraws the cassette to chamber 22 whereupon the gate valve isclosed.

[0049] Assuming that the cassette is now to be placed in depositionchamber 11, it may be that the operator first wishes to inspect thecassette and/or the cassette-to-robotic arm physical association. If so,robotic arm 23 is rotated to position the cassette at viewing station 14and/or 15. Robotic arm 23 now rotates to the position of depositionchamber 11, whereupon the vacuum within chambers 22 and 11 is equalized.The gate valve 24 that is associated with chambers 22 and 11 is nowopened, and robotic arm 23 deposits the cassette in an operativeposition within chamber 11. This gate 24 now closes, the vacuum withinchamber 11 is changed to whatever is required by the deposition processthat in operative in chamber 11, and vacuum deposition on the substratebegins.

[0050] After the cassette has progressed through all depositionchambers, the finished product cassette may be placed in park station18, by operation of robotic arm 23; for example, for visual inspection,park station 18 being at the same vacuum pressure as centrally-locatedvacuum chamber 22.

[0051] In the case of a cassette unload operation, the vacuum withinchambers 22 and 17 is equalized, the associated gate 24 is opened, thefinished product cassette is placed in load lock station 17 by operationof robotic arm 23, and the associated gate valve 24 is closed, all ofthese steps occurring with input load lock 25 is in its closed position.The vacuum within load lock station 17 is now controlled to be generallyequal to ambient atmospheric pressure, whereupon input load lock 25 isopened, and the finished product cassette is removed.

[0052] Non-limiting uses of the FIG. 1 system include the fabrication ofhigh quality amorphous, micro-crystalline, and poly-crystalline thinfilm silicon and related materials, devices and modules on a substratemember. As will be apparent, in accordance with this invention suchmaterials, devices and modules are fabricated on a flexible substratemember or web. As will be apparent, the present invention is alsoapplicable to virtually any technology where electronic devices aredesirable on a flexible substrate.

[0053]FIG. 2 is a side or Y-Z plane view of a linear, multiple chamber,vacuum deposition system 200 having three vacuum deposition chambers111, 112 and 113, an entry load lock 125, and an exit load lock station225 in accordance with the invention, and in which the substratecassette of the invention finds utility. As shown in FIG. 2, the variousstations of system 200 are separated by gate valves 124, a substratecassette transport means 201 is provided to transport the substratecassette between the various stations of FIG. 2, and a processcontroller 201 is provided to control system 200 and its substratecassette in much the same manner as described above relative to FIG. 1.

[0054] The present invention provides a new and unusual substratecassette or substrate magazine physical configuration for containing arelatively long, narrow and flexible substrate web that is used indeposition systems such as above described relative to FIGS. 1 and 2.

[0055] The systems of FIGS. 1 and 2 are conventionally used with arelatively small and rigid substrate member. However, in accordance withthis invention, a relatively long, narrow and flexible substrate webthat is contained within a roll-to-roll or reel-to-reel cassette ormagazine is provided for use in depositions systems of these generaltypes. Non-limiting examples of such a substrate web include polyemidefoil, stainless steel foil, and the like that are about 1 foot wide andabout 100 feet long. Of course, within the spirit and scope of thisinvention the substrate web can be longer/shorter or narrower/wider, asdesired.

[0056] The two physically spaced reel ends of the cassette respectivelycontain a supply reel/spool and a take-up reel/spool that are mounted torotate on fixed position and parallel axis. These two reels arephysically spaced so as to expose a relatively short depositionoperative run or length of the web; for example, a 1 foot by 1 foot webarea that extends between the two reels. This deposition operativesubstrate run is held under tension by virtue of two servo-controlleddrive motors that are connected one motor to each of the two reels.These two drive motors are servo controlled to advance the substrate webbetween a supply reel and a take-up reel, while at the same timemaintaining a constant tension in the web.

[0057] In one embodiment of the invention, the cassette is placed in adeposition chamber, and the substrate web is thereafter fed at acontrolled and continuous speed, or at a controlled step-by-step speed,from the supply reel to the take-up reel as a layer is deposited on thesubstrate web. In this case, the finished product comprises a singledeposition layer; for example, a single semiconductor layer.

[0058] In another embodiment of the invention, the cassette is placed ina first deposition chamber, and the substrate web is thereafter fed at acontrolled and continuous speed, or at a controlled step-by-step speed,from the supply reel to the take-up reel as a first layer is depositedon one side of the substrate web.

[0059] The cassette is then removed from the first deposition chamber(for example, to the centrally-located chamber 22 of FIG. 1). Somewherein the course of this operation (the place not being critical to theinvention), the substrate web is rewound from the take-up reel back ontothe supply reel.

[0060] The rewound cassette is then placed in a second depositionchamber, and the above-described process is repeated to thereby deposita second layer on the first deposited layer. As will be appreciated,this process can be repeated in order to deposit multiple layers ontothe substrate web. In this case, the finished product is a multiplelayer product.

[0061] The above two embodiments of the invention require that thesubstrate web be advanced from the supply reel to the take-up reelduring deposition, or between deposition chambers. As will beappreciated by those of skill in the related art, the speed at which thesubstrate web is advanced from the supply reel to the take-up reel iscontrolled in accordance with the deposition process that is operatingwithin each of the various deposition chambers.

[0062] In yet another embodiment of the invention, a multiple layerproduct may be produced as above described, wherein each individualshort substrate run that extends between the supply and take-up reels isoperated on to produce multiple layers, whereupon the substrate web isstep advanced, and the process is repeated. In this embodiment of theinvention, a rewind movement of the substrate web during deposition isnot required, and a rewind of the substrate web is not required betweendeposition chambers.

[0063] The use of a flexible substrate web as above described wherein arelatively long and narrow substrate web (for example, a substrate webthat is 100 feet long and 1 foot wide) is fed at a controlled speedthrough various deposition stations to produce electronic devices, suchas solar cells, thin film transistors, imaging devices or X-raydetectors has been found to be highly desirable. The present inventionprovides that cross-contamination of deposited layers is prevented.Since the layer deposition rates and the layer thickness of the variousdepositions may differ, both the speed of movement of the substrate webthrough the deposition areas and the physical length of the depositionareas as measured in the direction of this movement may be controlled asdesired.

[0064] While physical size is not critical to the invention, in anembodiment of the invention, circle 19 of FIG. 1 was about 3-feet indiameter, and the various peripheral chambers were generally cube-shapedand had a volume of about 50 liters.

[0065]FIG. 3 shows one of the FIG. 1 or FIG. 2 vacuum depositionchambers. Vacuum deposition chamber 30 of FIG. 3 is a PECVD chamberwherein a substrate cassette 31 in accordance with the invention isshown in its horizontal operative position between a RF plate 32 and theupper metal wall 33 of vacuum chamber 30. A gas injector tube 34provides a gas, such as silane, from which a plasma region 35 is formedby operation of RF plate 32 and its RF feedthru 36.

[0066] Cassette 31 is physically supported in an essentially horizontalX-Y plane by operation of two parallel and physically spaced trackmembers 37. A number of parallel and vertically adjustable legs 38 areprovided to enable adjustment of the vertical distance 39 that existsbetween RF plate 32 and cassette 31. A pump-out port 40 enables thevacuum within chamber 30 to be controlled as above mentioned.

[0067] In FIG. 3, cassette 31 is oriented such that its two reels extendparallel to the plane of the figure; that is, in the Y-direction. Inthis case, movement of the web-like substrate is in the X-Y plane. Asabove mentioned, two drive motors are provided to respectively controlthe two reels that are within cassette 31 (see motors 40 and 41 of FIG.5). One of these two drive motors 41 is shown in FIG. 3. The other drivemotor is directly behind motor 41 and is hidden from view by motor 41.

[0068] Usually, it is desirable to control the operating temperature ofchamber 30 and for this purpose, an externally-located heater elementand its insulation 42 are located in a well or cavity 43 that is locatedat the top of chamber 30. A thermocouple 44 and a temperature controlcircuit (not shown) operate to control heater 42 so as to maintainchamber 30 at a desired deposition temperature.

[0069]FIG. 4 is an enlarged view of cassette 31 as seen from the side ofFIG. 3; that is, as seen in the X-Z plane. Cassette 31 includes ahousing that is formed of an electrically-conductive material forgrounding purposes. Cassette 31 comprises a horizontally-extending upperwall 50 that extends between two elongated end housings 51 and 52 thatare generally square in cross-sectional shape, and whose central axis 53are parallel and extend in the Y-direction. Each of these two endhousings 51, 52 include a bottom and horizontally-extending wall 54 thatdefine a deposition opening area 155.

[0070] Housing 52 contains a first roll 55 of a flexible substratematerial 56 that extends through deposition opening 155, and terminatesat a second roll 56 that is contained within housing 52. If roll 55 isconsidered to be the above-described supply roll, then roll 56 is thetake-up roll. The length of the substrate web that is currently residentin deposition opening 155 is a relatively short substrate length uponwhich deposition occurs.

[0071] While the invention is not to be limited thereto, it is preferredthat the substrate web move continuously through deposition area 155 ata controlled rate so that all portions of the substrate web aresubjected to identical deposition characteristics. Without limitationthereto, the size of deposition opening 155 in an embodiment of theinvention was about 1 foot by 1 foot, whereas the length of thesubstrate web was about 100-feet.

[0072]FIG. 5 is a bottom view of cassette 31 as seen in FIG. 4. Thisview shows two doors 60 that are provided on the non-motor-drive side ofthe cassette to facilitate the insertion and removal of substrate rolls56 and 57 from cassette 31. This view also shows two drive mechanismsthat engage with two motors 40 and 41 that operate to maintain thedeposition run 155 of the substrate under tension so that thisdeposition run of the substrate occupies an essentially flat horizontalor X-Y plane.

[0073]FIG. 6 is a perspective view of another cassette in accordancewith the invention, wherein the cassette X-Y deposition plane 155 isaccurately established by a first idler roller 61 and a second idlerroller 62. In this embodiment, the cassette is housing enclosed as isshown in FIG. 4. However, the cassette external housing has not beenshown in FIG. 6 for purposes of convenience.

[0074] The cassette of FIG. 6 includes a rigid frame having a flat andgenerally square plate 66 that defines a centrally-located opening orwindow 155 that corresponds to the cassette's X-Y deposition plane. In anon-limiting embodiment of the invention, window 155 was about 1 foot by1 foot square.

[0075] Four rigid and parallel arms 67-70 stand upward and perpendicularfrom the four corners of plate 66, and the tops of these arms aresecurely maintained by operation of two rigid shafts 100, 101. Arms 67and 68 provide support for a first motor-driven substrate reel 64 andits underlying first idler roller 61, whereas arms 69 and 70 providesupport for a second independently motor-driven substrate reel 65 andits underlying second idler roller 62, all of which are bearingsupported within the respective arms 67-70.

[0076] In this embodiment of a cassette in accordance with theinvention, idler rollers 61 and 62 are mounted to ensure that therelatively short length of the substrate web that extends between thesetwo idler rollers is always at a fixed and constant X-Y depositionplane, a short distance above window 155.

[0077] Substrate reels 64 and 65 are motor driven about their respectiveaxes 71 and 72, whereas idler rollers 61 and 62 freely rotate abouttheir respective axes 73 and 74, all four axes of which are parallel,axes 71, 73 of which lie in a common X-Z plane, and axes 72, 74 of whichlie in a second common X-Z plane.

[0078] While the manner of independently driving reels 64 and 65 is notcritical to the invention, FIG. 6 shows a gear configuration 75 that isassociated with each of these two reels. In this manner, these two reelsare independently driven by two electric motors 40, 41 as shown in FIG.5.

[0079] As shown in FIG. 5, and in accordance with a feature of theinvention, the two electric motors 40, 41 are servo controlled by theoperation of a control means 83 so as to maintain the relatively shortlength of the substrate that extends between the two idler rollers 61,62 under a constant tension, thereby ensuring that the cassettedeposition plane 155 does not change as the effective diameter of thesupply reel decreases, and as the effective diameter of the take-up reelconcomitantly increases. This servo control of motors 40, 41 can beachieved by the use of two feedback signals 88, 89, and/or by the use ofa sensor 87 that responds to any Z-direction movement of this shortlength of the substrate away from the cassette's X-Y deposition plane155. In an embodiment of the invention, deposition plane 155 wasmaintained as a flat X-Y plane within plus or minus 1 mm.

[0080]FIG. 7 is an exploded view that shows how the two supply andtake-up reels 64 and 65 of FIG. 6 are constructed and arranged inaccordance with a feature of the invention in order to capture, andsecurely hold, the two opposite ends of the cassette relatively longsubstrate web; for example, the two 1 foot wide ends of a substrate webthat is 100 feet long. While FIG. 7 shows the construction of only reel64, the two reels 64, 65 are of identical construction.

[0081] The outer cylindrical surface of reel 64 is covered by an axiallysplit and relatively rigid metal cylindrical cover 90. In an embodimentof the invention, cover 90 was stainless steel about 0.35-inch thick.Cover 90 has an inner diameter that is only somewhat larger that theouter diameter of an underlying reel member 91 that is motor driven asabove described. However, cover 90 relatively freely slides over thecylindrical outer surface of motor-driven reel member 91.

[0082] The external surfaces at the two axial ends 92, 93 of cover 90each carry a C-ring 94 having an annular ramp 95 that faces downward inthe direction of a clamp ring 96. In operation, a 1 foot wide end of thesubstrate web (for example, a squared-off end) is manually inserted intoan axially extending slit 99 that is formed in cover 90, and therebyunder a portion of cover 90 so that this end of the substrate webphysically engages the outer surface of cylindrical member 91, and theinner surface of cylindrical cover 90.

[0083] In this position, the longitudinal axis 109 of the substrateextends perpendicular to the axis 71 of reel 64. The two clamp rings 96are now moved in a direction that is indicated by arrows 97. In somoving, clamp rings 96 radially compress both of the C-rings 94 and theunderlying cylindrical cover 90 so as to capture the end of thesubstrate web.

[0084]FIG. 8 shows an embodiment of the invention wherein the side 104of substrate 55 that faces away from FIG. 6 deposition window 56includes a 100 foot long and 1 foot wide protective layer 105 of arelatively thin and inert plastic material that operates to protect thedeposition layer(s) that is on the side 106 of the substrate web whenthe web is wound about a take-up reel.

[0085] Embodiments of the invention above described relate primarily tothe FIG. 1 and FIG. 2 multi-chamber deposition systems and to thesingle-chamber system of FIG. 3, which embodiments might be calledhorizontal deposition embodiments. However, this is not to be taken as alimitation on the spirit and scope of this invention. For example, thesystems of FIGS. 1, 2 and 3 may comprise vertical deposition systems;for example, systems wherein the length of the substrate web upon whichdeposition takes place occupies a generally vertical plane.

[0086]FIG. 9 is a partial showing of a vertically-oriented depositionchamber 90 in accordance with the invention, this construction andarrangement providing a high gas utilization rate. Chamber 90 includestwo vertically-oriented substrate cassettes 31 that are constructed andarranged, as above described, in accordance with the invention. That is,the relatively short deposition run 92 of the substrate web that iswithin each of the two cassettes 31 occupies a vertical or X-Z plane.

[0087] The construction of chamber 90 is generally symmetrical on eachside of a vertically-extending X-Z plane 91, and for convenience, theouter housing of deposition chamber 90 is not shown. Chamber 90 may be astand-alone chamber having function above described relative to FIG. 3,or a number of such chambers 90 may be used to provide a vertical or ahorizontal multi-chamber system having functions described relative toFIGS. 1 and 2.

[0088] In FIG. 9, the two vertical substrate runs 92 are processed atthe same time by utilizing a single RF plate 95, a single gas injector(not shown), and a single pump-out port (not shown), all of which arelocated generally on centrally-located X Z plane 91, thus effectivelyproviding two side disposed deposition chambers that can be accessed byway of gate valves (not shown). In addition, each horizontal side ofchamber 90 may include its own heater (not shown).

[0089] As above described, each of the two cassettes 31 includes a firstsubstrate reel 55 and a second substrate reel 56, these four reels beingindependently motor driven as above described by way of four gear trains99. Two individual cassette transport systems (not shown) can beprovided to individually transport each of the two cassettes 31, or asingle transport system (not shown) can be provided to transport bothcassettes 31.

[0090] Without limitation thereto, advantages of the above-describedinvention include (1) Independent substrate web processing can beprovided in each of a plurality of deposition chambers; (2) Nocross-contamination occurs as independent processing of the substrateweb progresses; (3) Deposition chambers in accordance with the inventioncan be used to process a rigid substrate member having a size of about12×12-inches (or larger), or can also be used to process a flexiblesubstrate web that is about 12-inches wide (or narrower/wider) and about100-feet long (or shorter/longer); (4) The inclusion of a redundantchamber(s) in a deposition system in accordance with the inventionreduces system down time; (5) The deposition chambers are useful in awide variety of deposition technologies, such as amorphous silicon,microcrystalline silicon, poly-silicon, copper indium selenides and itsvariants, CdTe, etc.; (6) The cost of a deposition process issubstantially less, thus providing a lower semiconductor product cost;(7) Multiple semiconductor layers can be deposited in any desiredsequence by using the deposition chambers in any desired depositionsequence; and (8) The invention can be used to fabricate advancedelectronic device structures, including, but not limited to, solarcells, thin film transistors, sensor arrays, X-ray detectors, etc.

[0091] While the invention has been described in detail while makingreference to various embodiments thereof, it is known that those skilledin the art will, upon learning of this invention, visualize yet otherembodiments that are within the spirit and scope of this invention.Thus, the above detailed description is not to be taken as a limitationon the spirit and scope of this invention.

What is claimed is:
 1. A method of depositing at least one materiallayer on a substrate member, comprising the steps of: providing at leastone deposition chamber for depositing said material layer; providing acassette having a first reel and a second reel that are physicallyspaced to define a deposition area therebetween; providing a relativelylong substrate web; winding said web onto said first reel and connectingan exposed end of said web to said second reel to thereby provide arelatively short length of said web extending between said first andsecond reels; placing said cassette within said at least one depositionchamber; depositing at least one material layer onto one side of saidrelatively short length of said web; and advancing said web from saidsupply reel to said take-up reel as said at least one deposition chamberdeposits said material layer onto said one side of said web.
 2. Themethod of claim 1 including the step of: providing a relatively longprotective web that physically engages an opposite side of said web. 3.The method of claim 1 including the steps of: providing a firstfixed-position idler roller that is associated with said first reel;providing a second fixed-position idler roller that extends parallel tosaid first idler roller and that is associated with said second reel;and threading said web over said first and second idler rollers toestablish said deposition area.
 4. The method of claim 2 wherein said atleast one deposition chamber is a vacuum deposition chamber that isoperable to a material selected from the group semiconductor, metal andtransparent conducting oxide.
 5. A method of depositing a plurality ofmaterial layers onto a substrate comprising the steps of: providing aplurality of deposition chambers; providing a cassette having a firstreel and a second reel that are physically spaced to define a depositionarea therebetween; providing a relatively long substrate web; windingsaid web onto said first reel and connecting an exposed end of said webto said second reel to thereby provide a relatively short length of saidweb at said deposition area; placing said cassette within a firstdeposition chamber; advancing said web from said supply reel to saidtake-up reel and concomitantly depositing a material layer on said web;removing said cassette from said first deposition chamber; placing saidcassette within another deposition chamber and concomitantly advancingsaid web from one reel to another reel as another material layer isdeposited on said web; and repeating said steps of removing saidcassette from a prior deposition chamber, placing said cassette withinanother deposition chamber and concomitantly advancing said web anddepositing a material layer on said web.
 6. The method of claim 5including the steps of: providing a first fixed-position idler rollerthat is associated with said first reel; providing a secondfixed-position idler roller that extends parallel to said first idlerroller and that is associated with said second reel; and threading saidweb over said first and second idler rollers to establish saiddeposition area.
 7. The method of claim 6 wherein said chambers arevacuum deposition chambers operable to individually deposit materialsselected from the group semiconductors, metals and transparentconducting oxides.
 8. The method of claim 7 including the step of:providing a relatively long protective web that is associated with aside of said web on which layer deposition does not occur.
 9. A methodof depositing the integer number N of layers onto a substrate,comprising the steps of: providing N deposition chambers; providing acassette having a first reel and a second reel that are physicallyspaced to define a deposition area between said reels; providing arelatively long substrate web; winding said web onto said first reel andconnecting an exposed end of said web to said second reel to therebyprovide a first relatively short length of said web at said depositionarea; placing said cassette within a first of said N depositionchambers; depositing a first layer on said first relatively short lengthof said web; placing said cassette within a second of said N depositionchambers; depositing a second layer on said first layer; repeating saidsteps of placing of said cassette within said deposition chambers anddepositing an associated layer until such time as said first relativelyshort length of said web contains N layers; step advancing said web fromsaid supply reel to said take-up reel to thereby provide a secondrelatively short length of said web at said deposition area; recyclingsaid cassette through said N deposition chambers to thereby provide Nlayers on said second relatively short length of said web; and repeatingsaid steps of step advancing and recycling until said relatively longweb contains a plurality of relatively short lengths, each short lengthcontaining N layers.
 10. The method of claim 9 including the steps of:providing a first fixed-position idler roller that is associated withsaid first reel; providing a second fixed-position idler roller thatextends parallel to said first idler roller and that is associated withsaid second reel; and threading said web over said first and secondidler rollers to establish a material deposition plane that remainsconstant as said web is advanced between said reels.
 11. The method ofclaim 10 including the step of: providing a relatively long protectiveweb that physically engages a side of said web on which layer depositiondoes not occur.
 12. The method of claim 11 wherein said depositionchambers are vacuum deposition chamber each operable to deposit amaterial layer on said web, said material layer selected from the groupsemiconductor layer, metal layer and transparent conducting oxide layer.13. A method of manufacturing a relatively substrate web that containsone or more layers selected from the group semiconductor layer, metallayer and transparent conducting oxide layer on a first surface of saidweb, comprising the steps of: providing a substrate cassette having afirst reel and a second reel that rotate on parallel but physicallyspaced axes; providing a first idler roller mounted at a fixed positionrelative to said first reel, said first idler roller rotating on an axisthat extends parallel to said the of said first reel; providing a secondidler roller mounted at a fixed position relative to said second reel,said second idler roller rotating on an axis that extends parallel tothe axis of said second reel; said first and second idler rollers beingspaced to define a fixed-position deposition plane at a location betweensaid first and second idler rollers; winding said web about said firstreel, threading an exposed end of said web over said first and secondidler rollers, and connecting said exposed end of said web to saidsecond reel; and placing said substrate cassette within one or moredeposition chambers and advancing said web between said first and secondreels as one or more layers are concomitantly deposited on substantiallythe entire length of said first surface of said web.
 14. The method ofclaim 13 including the step of: providing a relatively long protectiveweb that physically engages a side of said web that is opposite saidfirst side of said web.
 15. The method of claim 13 including the stepsof: providing a first motor to control rotation of said first reel;providing a second motor to control rotation of said second reel; andcontrolling said first and second motors in a manner to produce saidstep of advancing said web between said first and second reels in amanner to maintain a substantially constant tension in a relativelyshort length of said web that extends between said first and secondidler rollers.
 16. The method of claim 15 wherein said first and secondmotors are electrical motors.
 17. A semiconductor manufacturing processcomprising the steps of: providing a substrate cassette having a firstreel and a second reel that independently rotate on parallel andphysically spaced axes and that are physically spaced to define adeposition plane at a location between said first and second reels;providing a relatively long and flexible substrate web having one endconnected to said first reel, having an exposed end connected to saidsecond reel, and having a relatively short intermediate length of saidweb exposed at said deposition plane; providing at least onesemiconductor deposition chamber containing said substrate cassette; andadvancing said web between said first and second reels as at least onesemiconductor layer is concomitantly deposited on substantially theentire length of one surface of said web.
 18. The method of claim 17including the step of: controlling said step of advancing of said webbetween said first and second reels in a manner to maintainsubstantially a constant tension in a said relatively short intermediatelength of said web.
 19. A reel-to-reel cassette containing a substratecomprising: a first reel and a second reel that rotate on parallel andphysically spaced axes, a space between said axes defining a relativelyshort deposition plane; and a relatively long and flexible substrate webwound about said first reel and an exposed end of said web connected tosaid second reel.
 20. The cassette of claim 19 including: a first drivegear for providing rotation of said first reel; and a second drive gearfor providing rotation of said second reel; said first and second gearsbeing operable to produce movement of said web between said first andsecond reels.
 21. The cassette of claim 20 including: a first idlerroller mounted at a fixed position relative to said first reel, saidfirst idler roller rotating on an axis that extends parallel to the axisof said first reel; a second idler roller mounted at a fixed positionrelative to said second reel, said second idler roller rotating on anaxis that extends parallel to the axis of said second reel; said firstand second idler rollers being spaced to define said deposition plane ata location between said first and second idler rollers; and said webextending over said first and second idler rollers to define arelatively short deposition plane on one surface of said substrate web.22. The cassette of claim 19 wherein each of said first and second reelsincludes: a centrally located and cylindrical driven member; a hollowcylindrical member encircling said driven member with an internalcylindrical surface of said hollow cylindrical member in physicalengagement with an external cylindrical surface of said driven member;an axially extending slit formed in said hollow cylindrical member; oneend of said substrate web being inserted into the axial slit of thehollow cylindrical member of said first reel; an opposite end of saidsubstrate web being inserted into the axial slit of the hollowcylindrical member of said second reel; and means applying a radiallyinward force to the hollow cylindrical members of said first and secondreels to thereby secure said ends of said substrate web between saidinternal cylindrical surfaces of said hollow cylindrical members andsaid external cylindrical surfaces of said driven members.
 23. Thecassette of claim 22 including: a first drive gear for providingrotation of the driven member of said first reel; and a second drivegear for providing rotation of the driven member of said second reel;said first and second gears being operable to produce movement of saidweb between said first and second reels.
 24. A manufacturing systemcomprising: a substrate cassette having a first reel and a second reelthat independently rotate on parallel and physically spaced axes; saidfirst and second reels being physically spaced to define a relativelysmall deposition plane at a location between said first and secondreels; a relatively long and flexible substrate web having a majorportion thereof wound about said first reel, having an exposed endconnected to said second reel, and having a relatively shortintermediate length of said web exposed at said deposition plane; atleast one deposition chamber selected from the group semiconductordeposition camber, metal deposition chamber and transparent conductingoxide deposition chamber containing said substrate cassette; and drivemeans for advancing said web between said first and second reels as atleast one layer is deposited on substantially the entire length of oneside surface of said web.
 25. The system of claim 24 including: a firstidler roller mounted at a fixed position relative to said first reel,said first idler roller rotating on an axis that extends parallel to theaxis of said first reel; and a second idler roller mounted at a fixedposition relative to said second reel, said second idler roller rotatingon an axis that extends parallel to the axis of said second reel; saidfirst and second idler rollers having said web threaded thereover andbeing physically spaced to define said relatively short intermediatelength of said web at a location between said first and second idlerrollers.
 26. The system of claim 24 including: a first motor connectedto control rotation of said first reel; a second motor connected tocontrol rotation of said second reel; and means controlling said firstand second motors in a manner to advance said web between said first andsecond reels and concomitantly maintain a substantially constant tensionin said relatively short intermediate length of said web.